This invention relates to compositions of matter classified in the art of chemistry as gas generants more particularly as gas generants designed to produce relatively cool gas containing minimal components having toxic effects on warm blooded animals and to processes for their preparation and use.
N,N'-dihydroxyethane diamide (dihydroxyglyoxime, DHG) based propellants are known. Their combustion takes place at relatively high temperature (about 980.degree. C. or more) and the evolved gases contain significant quantities of HCN (in the 4.0 mole percent range with exact values, of course, depending on the particular formulation).
There is a growing need for gas generator systems capable of producing quantities of gas at final temperatures in the range of 50.degree. to 150.degree. C. These applications are in the fields of inflatable or rigid structures such as helicopter flotation bags, cargo pallet soft-landing bags, aircraft escape slides, inflatable life rafts and similar items. The low temperture of the gases is required because the inflatable structures are fabricated from materials, frequently synthetic polymeric films and fabrics, such as nylon fabric bonded to polyurethane film or neoprene coated rubber combined with rayon fabric, which are rendered unusable by exposure to higher temperatures. To avoid attack on the structural materials, the evolved gases must be chemically inert to them and, as at least some potential uses require that the gases be physiologically inert to men and other warm blooded animals, the evolved gases must have minimal amounts of toxic components. A number of alkali metal azide based gas generant compositions suitable for automobile air bags have been successfully designed in conjunction with proper inflator units which are highly satisfactory and are reportedly being commercially developed.
Azides themselves are toxic materials and require precautions to avoid exposure during fabrication of any device employing them and care to avoid exposure during later use or disposal of any such device. Accordingly, a non-azide based system having the aforementioned desired attributes for its evolved gases would be of interest to the art. The present invention provides propellant compositions which, taken together with downstream coolants, are able to provide the desired cool gas containing low levels of hydrogen cyanide.